#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int H, W;
    cin >> H >> W;
    vector<mint> fact(H + W + 1), inv(H + W + 1), a(H + 1), b(W + 1);
    fact[0] = 1;
    for(int i = 1; i <= H + W; i++) fact[i] = i * fact[i - 1];
    inv[H + W] = 1 / fact[H + W];
    for(int i = H + W; i >= 1; i--) inv[i - 1] = i * inv[i];

    for(int i = 0; i <= H / 2; i++) a[H - i] = inv[i] * inv[H - 2 * i];
    for(int i = 0; i <= W / 2; i++) b[W - i] = inv[i] * inv[W - 2 * i];

    auto c = convolution(a, b);

    mint ans;
    for(int i = (H + W) / 2; i <= H + W; i++) ans += fact[i] * c[i];

    cout << ans.val() << '\n';
}